/**
 * 	Copyright 2011 RK
 *
 * 	Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 * 	You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *	limitations under the License.
 *
 */
package queryable.store;

import java.rmi.server.UID;
import java.util.UUID;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;


/**
 * Base implementation for {@link IStore}
 * @author RK
 *
 */
public abstract class AbstractStore<T> implements IStore<T>
{
	public	static class UIDGenerator implements IDGenerator
	{
		/*
		 * (non-Javadoc)
		 * 
		 * @see queryable.store.sql.JDBCStore.IDGenerator#nextID()
		 */
		@Override
		public Object nextID()
		{
			return new UID().toString();
		}
	}

	public static class UUIDGenerator implements IDGenerator
	{

		/*
		 * (non-Javadoc)
		 * 
		 * @see queryable.store.sql.JDBCStore.IDGenerator#nextID()
		 */
		@Override
		public Object nextID()
		{
			return UUID.randomUUID().toString();
		}
	}

	public static class SimpleLongIncrementor implements IDGenerator
	{
		private AtomicLong	insertCount	= new AtomicLong(System.currentTimeMillis());

		/*
		 * (non-Javadoc)
		 * 
		 * @see queryable.store.sql.JDBCStore.IDGenerator#nextID()
		 */
		@Override
		public Object nextID()
		{
			return this.insertCount.incrementAndGet();
		}
	}

	public	static class SimpleIntegerIncrementor implements IDGenerator
	{
		private AtomicInteger	insertCount	= new AtomicInteger(0);

		/*
		 * (non-Javadoc)
		 * 
		 * @see queryable.store.sql.JDBCStore.IDGenerator#nextID()
		 */
		@Override
		public Object nextID()
		{
			return this.insertCount.incrementAndGet();
		}
	}

	private final ReadWriteLock lock = new ReentrantReadWriteLock();
	protected final Lock readLock = lock.readLock();
	protected final Lock writeLock = lock.writeLock();

	/*
	 * (non-Javadoc)
	 * @see queryable.store.IStore#readLock()
	 */
	@Override
	public Lock readLock()
	{
		return this.readLock;
	}

}
